1. Field of the Invention
This invention relates to circuit breakers, and more particularly it is concerned with a puffer type gas circuit breaker formed therein with two paths for blowing gas therethrough.
2. Description of the Prior Art
Puffer type gas circuit breakers of simple construction are known as circuit breakers of high capacity.
A puffer type gas circuit breaker comprises an interrupting unit mounted in an enclosure filled with a charge of arc extinguishing gas (e.g. SF6 gas) of uniform pressure. The interrupting unit includes a puffer chamber composed of a piston and a cylinder either of which is driven to compress the arc extinguishing gas in the puffer chamber. The piston or cylinder which is driven is connected to a movable contact, so that the contacts are brought out of engagement with each other as the arc extinguishing gas in the puffer chamber is compressed. The arc extinguishing gas compressed in the puffer chamber is led through an insulating nozzle and blown against the electric arc to extinguish the same.
The insulating nozzle is an important factor concerned in determining the current interrupting performance of circuit breakers of this type. Thus various improvements have been made in or relating to the insulating nozzle so as to greatly increase the current interrupting capabilities of the breakers.
Proposals have been made to use a double flow structure in which two streams of gas are formed instead of a single flow structure in which a single stream of gas is formed and directed from the puffer chamber to the outside through the throat of a single insulating nozzle, in order that the current interrupting capability may be greatly increased.
The double flow structure of the prior art represents a conversion of the single flow structure into the double flow structure in which the characteristics of the single flow structure are still retained. Thus no structure best suiting the double flow of gas has ever been produced. Moreover, one of the paths of flow of gas according to the prior art is formed by a metallic nozzle constituting a hollow contact. Because of this arrangement, it has hitherto been impossible for the nozzles to perform an arc extinguishing action satisfactorily.